A Coupled LBM‐FDEM Framework for Simulating Solute Transport and Mineral Dissolution Under H‐M‐C Conditions

Abstract

The injection of CO2 into geological reservoirs can acidify the reservoir environment, leading to the dissolution of mineral grains and increasing the risk of CO2 leakage. A deeper understanding of these micro‐scale dissolution mechanisms is therefore essential for the safety of geological CO2 sequestration. To address this challenge, we develop a multi‐field coupled simulation framework that integrates the Lattice Boltzmann Method (LBM) with the Finite‐Discrete Element Method (FDEM) to model solute transport and mineral micro‐structure dissolution. The framework incorporates a geometric mapping detection scheme and an improved momentum exchange algorithm to capture fluid‐solid interactions. Furthermore, a novel updating scheme for dissolution rates and solute concentrations is proposed, explicitly accounting for mass conservation and complex mineral morphology. A dynamic geometric topology updating algorithm is also proposed to track the morphological evolution of mineral grains. The accuracy and capability of the LBM‐FDEM framework are validated through several numerical benchmarks, including particle settling, solute release from a moving particle, dissolution of polymorphic particles, and reactive transport within a non‐uniform channel, yielding excellent agreement with existing solutions. Finally, this proposed method is applied to investigate the spatiotemporal evolution of fracture dissolution under varying Péclet numbers. The numerical results reveal that under diffusion‐dominated low Péclet regimes, product accumulation restricts dissolution to the upstream inlet, yielding a typical face dissolution pattern. Conversely, strong advection under high Péclet conditions drives rapid reactant penetration, triggering a uniform channelized widening along the entire fracture. Ultimately, this framework demonstrates significant potential for investigating complex hydro‐mechanical‐chemical couplings in subsurface engineering.